Jonathan Spencer Willis (April 5, 1830 – November 24, 1903) was an American politician from Milford in Kent County, Delaware.

Willis was born in Oxford, Maryland, attended the district schools there and studied under private tutors.

He taught school seven years and then entered the ministry of the Methodist Episcopal Church, serving charges in Maryland, Delaware, Philadelphia, New York City, and Stamford, Connecticut.

He retired from the ministry in 1884 and settled on a farm near Milford and engaged in fruit growing.

He was an unsuccessful candidate, however, for reelection in 1896 to the 55th Congress, and returned to the full effort of agricultural pursuits.